The present application relates to a liquid crystal display panel having a liquid crystal inlet, and more particularly to a liquid crystal display panel in which a low temperature insulating film is formed after completion of formation of a resin film.
A liquid crystal display panel is used as a display panel in many electronic apparatuses because the liquid crystal display panel has the features such as light weight, slimness and low power consumption as compared with a Cathode Ray Tube (CRT). The liquid crystal display panel is such that an alignment of liquid crystal molecules arranged in a predetermined direction is changed by application of an electric field to change an amount of light transmitted through a liquid crystal layer, thereby displaying an image on the liquid crystal display panel. With regard to such a liquid crystal display panel, reflection type one, transmission type one, and semi-transmission type one including both the reflection type one and the transmission type one exist. In this case, in the reflection type liquid crystal display panel, an outside light is made incident to a liquid crystal layer, and is reflected by a reflective plate to be transmitted through the liquid crystal layer again to be emitted. Also, in the transmission type liquid crystal display panel, an incident light radiated from a backlight unit is transmitted through a liquid crystal layer.
A longitudinal electric field system and a transverse electric field system are known as those used in a method of applying an electric field to a liquid crystal layer of the liquid crystal display panel. With the liquid crystal display panel using the longitudinal electric field system, an electric field directed approximately in the longitudinal direction is applied to liquid crystal molecules through a pair of electrodes disposed so as to hold the liquid crystal layer between the paired electrodes. A liquid crystal display panel having a Twisted Nematic (TN) mode, a liquid crystal display panel having a Vertical Alignment (VA) mode, a liquid crystal display panel having a Multi-domain Vertical Alignment (MVA) mode or the like is known as the liquid crystal display panel using the longitudinal electric field system. With the liquid crystal display panel using the transverse electric field system, a pair of electrodes is provided in an inner surface side of one of a pair of substrates disposed so as to hold the liquid crystal layer between the paired substrates with the paired electrodes being insulated from each other. Also, an electric field directed approximately in the transverse direction is applied to the liquid crystal molecules. A liquid crystal display panel having an In-Plane Switching (ISP) mode in which a pair of electrodes does not overlap in terms of planar view, and a liquid crystal display panel having a Fringe Field Switching (FFS) mode in which a pair of electrodes overlaps in terms of planar view are known as the liquid crystal display panel using the transverse electric field system.
Of them, in the liquid crystal display panel having the IPS mode, a pair of electrodes composed of a pixel electrode and a common electrode is formed in a pectinate shape so that the paired electrodes are engaged with each other with the paired electrodes being electrically insulated from each other. Also, the transverse electric field is applied across the pixel electrode and the common electrode. The liquid crystal display panel having the IPS mode has such an advantage that its view angle is wider than that of the liquid crystal display panel having the longitudinal electric field.
In the liquid crystal display panel having the FFS mode, a pair of electrodes is composed of a common electrode and a pixel electrode. Also, pairs of common electrodes and pixel electrodes are disposed in different layers, respectively, through an insulating film. A slit-like opening is provided either in the common electrode or in the pixel electrode on the liquid crystal layer side, and the electric field oriented approximately in the transverse direction and passing through the slit-like opening is applied to the liquid crystal layer. The liquid crystal display panel having the FFS mode has been used recently in many cases because the liquid crystal display panel having the FFS mode has an effect that the wide view angle can be obtained and also the image contrast can be improved.
With regard to the liquid crystal display panel having the FFS mode, a liquid crystal display panel is known in which as disclosed in FIG. 2 of Japanese Patent Laid-Open No. 2009-036800 (Patent Document 1), a pixel electrode is formed approximately on the same plane as that of a Thin Film Transistor (TFT) serving as a switching element. Also, a liquid crystal panel is known in which as disclosed in FIG. 2 of Japanese Patent Laid-Open No. 2009-047839 (Patent Document 2), both a common electrode and a pixel electrode are disposed above a TFT.
Among these, in the liquid crystal panel having the FFS mode in which both the common electrode and the pixel electrodes are disposed above the TFT, a surface of the TFT and the like is covered with an interlayer film made of an acrylic resin or the like. A lower electrode made of a transparent conductive material is formed on a surface of the interlayer film. Also, an upper electrode is formed on a surface of the lower electrode sandwiching an inorganic insulating film. The lower electrode can be operated as any of the pixel electrode and the common electrode. The interlayer film planarizes the irregularities of the TFT and the like, and both the upper and lower electrodes can be formed above the TFT, which results in an increased aperture ratio.